MMA fighter Johnny Case admitted to police he performed a "leg sweep" on his ex-girlfriend during an altercation last week -- but insists he was merely defending himself against another trained fighter.
It's all spelled out in the police report, obtained by TMZ Sports ... which shows the ex-girlfriend called the Las Vegas Metro Police Dept. on April 1 to report a domestic violence incident.
The woman -- who is a professional fighter -- told cops she was hanging out with Case in her apartment when he told her he wanted to have sex.